Abstract: To simplify fitting, securing and cleaning of a water trap to/from a washbasin or sink, there is provided a washbasin valve which has a water trap integral therewith and which forms a unit that can be inserted into and secured to the bottom of a washbasin, therewith a water drainage system can be connected directly to the valve. The washbasin valve is fitted by pushing the valve into a hole in the bottom of the basin and securing the valve therein, whereafter the valve is connected directly to a drain pipe. In cleaning the water trap, the seal is drawn-up out of the valve with the water drainage system still connected. No water will be spilled unnecessarily onto the floor beneath the washbasin in so doing.